It's impressive with the trial and error work to try to reach goal of being able to emulate the mechanisms of the hardware protection. I wonder how long it will take with emulating the protection of later (1990s era) Atari games (sloop?) whenever work begins on emulating that protection.
Maybe have a poll of which of the two is more challenging: Atari's sloop versus Seibu's. COP ie: not counting anything that uses Dallas MCU protection